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Biomedical subjects

I B Tager

Publications and source records attributed to I B Tager.

At least 73 records · Page 4Linked to original sources
PubMed1989

Acute lower respiratory illness in childhood as a predictor of lung function and chronic respiratory symptoms.

This study investigated the relationship of acute lower respiratory illness (LRI) to level and change in level of forced expiratory volumes in a cohort of 801 children, followed longitudinally for a maximum of 13 yr. The co-occurrence of respiratory illness before 2 yr of age and two or more LRI during a single surveillance year was associated with a 20.3% lower mean cross-sectional level of FEF25-75, and with reduced longitudinal change in level of FEF25-75. The effect of LRI on lung function was uniformly stronger for boys than for girls. Of the children with illness before 2 yr of age and two or more LRI, six of 14 were male asthmatics with mean levels of FEF25-75 that were lower than those of other asthmatic children. Pneumonia and/or hospitalization for respiratory illness prior to the onset of study were associated with lower cross-sectional levels of forced expiratory volumes at entry to the study, even when asthmatics/persistent wheezers were eliminated from the analysis (6.1% lower level of FEV1 for a nonasthmatic boy with previous hospitalization versus a nonasthmatic boy without hospitalization). In the longitudinal analysis, pneumonia and/or hospitalization were associated with slower increase in level of forced expiratory volumes, even after adjusting for "ever diagnosis of asthma/current any wheeze" (starting at the same leve, after eight years a boy with hospitalization would develop a 5.0% lower FEV1 than a boy without hospitalization). Acute LRI also was evaluated as a predictor of chronic respiratory symptoms.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Disease↗
PubMed1988

Smoothing methods for epidemiologic analysis.

The development of techniques for fitting non-parametric smooth curves has resulted in less restrictive regression models. We discuss the ideas underlying such smoothing algorithms, develop their application to epidemiologic studies and address specific issues, such as coping with correlated errors. An example illustrates a particular smoothing approach, as applied to pulmonary function data. The method provides new insight into the effect of smoking on pulmonary function. The discussion offers some qualitative comparisons between smoothing methods and conventional linear models.

Adult↗
PubMed1988

The natural history of forced expiratory volumes. Effect of cigarette smoking and respiratory symptoms.

Epidemiologic investigations into the natural history of airway obstructive disease have focused on both the growth and decline of lung function measurements. Although a general picture has emerged as to overall patterns of growth/decline, uncertainty remains with regard to important details of these patterns. Pulmonary function data from subjects aged 5 yr and and older who participated in any or all of the first 10 annual surveys of the East Boston population-based study have been used to investigate patterns of growth and decline of lung function derived from maximal forced expiratory maneuvers. At each annual survey, subjects completed a standardized respiratory illness and smoking questionnaire and provided forced expiratory volume-time curves from which forced vital capacity (FVC) and forced expiratory volume in one second (FEV1) were derived. A nonparametric curve smoothing method was used to provide an overall summary of growth and decline of each measure of function. Asymptomatic, nonsmoking males demonstrated a pattern of growth of FEV1 that included a prolonged plateau phase or period of slow, continued growth from ages 23 to 35 yr. Decline in lung function began after this period and occurred in two phases that averaged about -20 and -30 ml/yr. In contrast, no plateau phase was observed for male current smokers. In these smokers, decline in FEV1 began in the early part of the third decade at a rate only slightly greater than that observed for nonsmokers (-25 to -30 ml/yr). Similar patterns and rates of decline were observed for females, although the presence of a plateau phase was less clearly discernible. These data suggest that a major effect of cigarette smoking on lung function decline involves the premature onset of a "normal" rate of decline in function and, to a lesser extent, more rapid rates of decline later in life and that the pattern and magnitude of decline is similar in males and females.

Adolescent↗
PubMed1987

Assessment of the usefulness of helium-oxygen maximal expiratory flow curves in epidemiologic studies of lung disease in children.

Density dependence of maximal expiratory air flow (DD) has been used in adults as a test of early obstructive airway disease (OAD). Whether DD is useful as an epidemiologic tool to identify childhood risk factors for OAD is not known. In a population-based sample of 133 children 8 to 23 yr of age, we calculated density dependence at 50 and 25% of vital capacity (DD50 and DD25) (the ratios between maximal expiratory flow rates breathing helium-oxygen and air gas mixtures at each of these lung volumes), and the volume of isoflow (VisoV) (the lung volume, expressed as a percentage of vital capacity, at which maximal flow rates when breathing each gas mixture are equal), measured airway responsiveness using eucapnic hyperventilation with cold air, and obtained health and household information with questionnaires. Mean levels (+/- SD) of DD50, DD25, and VisoV were: 1.49 +/- 0.14, 1.37 +/- 0.18, and 10.7 +/- 10%. The DD50 significantly increased with age in these growing children (p less than 0.05), but DD50 was found to be significantly lower (1.42 +/- 0.14 versus 1.52 +/- 0.13; p less than 0.01) among children with nonspecific bronchial hyperresponsiveness. The DD50 also was significantly reduced among children with a history of a recent upper respiratory tract illness (URI) (p less than 0.01). There were no significant associations of DD with history of asthma, personal smoking, parental smoking, or respiratory illness during infancy. The reproducibility of DD50 was assessed on a subsample of 90 subjects in whom DD was measured during 2 surveys 1 yr apart.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1987

The effect of maternal cigarette smoking on the pulmonary function of children and adolescents. Analyses of data from two populations.

To evaluate the role of the use of different analytical techniques in determining differences in the reported effects of passive smoking in children and adolescents, data sets from 2 studies that had previously reported divergent results were subjected to a uniform analytic procedure using a first-order autoregressive model (AR1). Although the populations studied differed in age distribution and the frequency of both personal and maternal smoking, the assumptions of the AR1 model were met by both data sets, and the models developed fit both data sets well. Coefficients for personal smoking from the study-specific models were almost identical. An effect of maternal smoking on FEV1, which has been reported for the East Boston data, again was observed, but no such effect was observed for the Tucson data set. These findings suggest that the differences in reported results are not related simply to model specificity and that real differences in exposure or response to exposure may be occurring in different climatic situations. Such differences need to be taken into account in any assessment of indoor exposure to potentially noxious agents.

Adolescent↗
PubMed1987

Assessment of genetic and nongenetic influences on pulmonary function. A twin study.

To better understand the extent to which familial similarities in pulmonary function (PF) are attributable to genetic rather than to shared environmental influences, we studied the twinship aggregation of PF in 256 monozygotic (MZ) and 158 dizygotic (DZ) adult twin members of the Greater Boston Twin Registry. Genetic influences on various spirometric measures were estimated with twinship intrapair correlations adjusted using a regression model to control for similarities in the anthropomorphic characteristics of twins, and for the effects of a number of environmental factors that included childhood respiratory illness, occupational dust exposure, and smoking history. A significant influence of smoking on all air-flow measures was observed in this population for whom genetic similarities were adjusted. However, highly significant adjusted intrapair correlations for all spirometric measures, ranging from 0.52 to 0.76, were observed for the MZ twins. The intrapair correlations for the DZ twins were approximately one-half the magnitude of those for the MZ twins. These data suggest that a large proportion of the measured variability in PF may be accounted for by genetic influences other than those associated with body size.

Adult↗
PubMed1987

Occurrence of asthma, nonspecific bronchial hyperresponsiveness and atopy. Insights from cross-sectional epidemiologic studies.

Data from various different types of cross-sectional studies are reviewed in order to examine hypotheses about the etiology of asthma and to more precisely define its relationship with nonspecific bronchial hyperreactivity (NSBH). Although cross-sectional studies have not clarified the precise etiologic links, they have established that NSBH and atopy are linked to the occurrence of asthma and to each other. In children, evidence supports the hypothesis both that atopy is a cause of asthma and that atopic diathesis is the most frequent trigger for NSHB. In adults, the associations are more complex, although in a small subset findings are similar to those in children. It is concluded that further general population-based or clinical epidemiologic cross-sectional studies based on questionnaires will contribute little more to explaining these associations. Criteria are presented for the further application of case-control studies to maximize their use in examining hypotheses of asthma etiology.

Adult↗
PubMed1986

Determinants of response to eucapneic hyperventilation with cold air in a population-based study.

A population-based, epidemiologic investigation conducted in children, adolescents, and young adults analyzed the response to eucapneic hyperventilation with cold air as a continuous variable to better define factors that influence the expression of bronchial responsiveness. Among respiratory illness/symptom variables, only the report of asthma or persistent wheeze in the previous year and the report of a respiratory illness that led to activity restriction were significantly associated with response to cold air. Furthermore, a low, prechallenge FEF/FVC ratio was a significant predictor of response, especially among those subjects who reported a respiratory illness that led to activity restriction. This relationship was not observed for a low prechallenge FEF.

Adolescent↗
PubMed1985

Variability in the intradermal and in vitro lymphocyte responses to PPD in patients receiving isoniazid chemoprophylaxis.

Much attention has been focused on problems related to the interpretation of the tuberculin (Tb) skin test in terms of the "booster" phenomenon observed with repeated skin testing. However, relatively little attention has been given to the problem of the interpretation of repeat Tb skin tests in patients who have been given isoniazid (INH) chemoprophylaxis. Sixteen female hospital workers who were receiving INH for asymptomatic recent conversion of their Tb skin test, and 1 male physician under treatment with INH and rifampin for active tuberculosis as a result of a patient exposure, were studied over a 1-yr period. Intradermal skin tests with 5 tuberculin units purified protein derivative (PPD) and assessment of in vitro lymphocyte proliferation and production of leukocyte inhibitory factor on exposure to PPD were performed on 4 occasions at 3-month intervals-3 during therapy and 1 after completion of therapy. Four of 10 patients tested on all occasions showed at least 1 negative Tb skin test. In 2 of 4, the reversions were not stable. Considerable variability was observed between results of skin tests and in vitro lymphocyte responses, and no one in vitro lymphocyte response to PPD was adequate to identify the presence of delayed hypersensitivity to PPD. On the basis of these data, it is concluded that the presence of a single negative PPD skin test during or shortly after the completion of INH chemoprophylaxis does not constitute sufficient evidence to conclude that a patient has had a stable skin test reversion. Confirmation of the loss of tuberculin reactivity requires the in vitro assessment of lymphocyte responses to PPD both in terms of proliferation and the production of a lymphokine(s).

Cross Infection↗
PubMed1985

The relationship of respiratory infections in early childhood to the occurrence of increased levels of bronchial responsiveness and atopy.

We assessed the relationship of antecedent acute respiratory illness to the occurrence of airway responsiveness and atopy in a population-based cohort of 194 children 12 to 16 yr of age from East Boston, Massachusetts. A history of croup or bronchiolitis as reported by their parents was determined at study onset when the children were 5 to 9 yr of age. During the second and third years of the study, acute respiratory illness was assessed. Five years after the prospective respiratory illness assessment, airway responsiveness was evaluated with eucapneic hyperpnea to subfreezing air, and atopy was evaluated with skin tests to 4 environmental antigens. Both a prior history of croup of bronchiolitis (OR = 2.29, p = 0.04) and greater than 2 acute lower respiratory illnesses (OR = 3.72, p = 0.012) were associated with increased levels of airway responsiveness. Neither index of respiratory illness experience was related to the presence of atopy. However, maternal cigarette smoking was significantly associated with atopy in these children (OR = 2.24, p = 0.02). These data suggest that respiratory illness in early life is associated with airway hyperresponsiveness as measured later in childhood. The data further suggest the need for longitudinal studies to better assess the etiologic role of these potential risk factors.

Adolescent↗
PubMed1985

Effect of cigarette smoking on the pulmonary function of children and adolescents.

The effect of personal cigarette smoking on the growth of lung function in children and adolescents has been assessed in a longitudinal study of a group of 669 subjects 5 to 19 yr of age at initial examination. Subjects were seen annually and assessed with standard questionnaires and measurements of forced expiratory volume in one second (FEV1) and forced expiratory flow during the middle half of the forced vital capacity (FEF25-75). Multiple regression analysis revealed that after correction for previous FEV1 or FEF25-75, age, sex, height, change in height, interactions of age and change in height, and sex and height, and mother's smoking, the personal smoking by the children led to a significant decrease in the rate of growth of FEV1 (p less than 0.001) and FEF25-75 (p = 0.033). On the basis of this analysis, it is estimated that, on average, children who begin to smoke at 15 yr of age and continue to smoke would achieve only 92% (95% confidence limit, 87 to 96%) of their expected FEV1 and 90% (95% confidence limit, 81 to 99%), of their expected FEF25-75 at 20 yr of age. These data suggest that relatively small amounts of cigarette use (median total consumption of 7,300 cigarettes in this study) by adolescents can lead to significant effects on the growth of lung function.

Adolescent↗